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This page describes how to connect the Devantech SRF02 Ultrasound sensor to a FireFly sensor node. This could be used for ranging, or with multiple FireFly nodes, difference in time of flight ranging can be done using the "fake" mode of the SRF02.

By soldering a header on top of the receptical, it is possible to program and receive debugging data from a node even with the ultrasound module attached. Only do this for boards that will be used for debugging. Otherwise just solder directly onto the receptical.

Adding a jumper to the Ultrasounds UART TX line is required for programming the FireFly node while the ultrasound board is attached. Since the programming board uses the same UART lines, if the ulrasound TX is left connected during downloads, the ultrasound board may send signals that corrupt the FireFly firmware.

The SRF02 can be instructed to listen only for the transmission from another module using a command of 0x56,0x57 or 0x58 depending onwhat range type you wish to be generated. The 40khz pulse can then be fired from another module with a command of 0x5C, this will just transmit and not listen for a response.